Tatiana Maslany’s astounding portrayal of 11 incredibly diverse clones on BBC America’s Orphan Black has turned her into one of the most talked about actors — and there is one person the 28-year-old consistently cites for helping her bring this award-winning role to life: Kathryn Alexandre.

“I could cry thinking about her,” Maslany said of Alexandre, her Orphan Black clone double, during a Screen Actors Guild Foundation interview. “She’s so amazing. She memorizes all of the lines, all of my blocking, all of her blocking, my mannerisms, my impulses; she, somehow, memorizes all of that and gives it back to me with a performance I can play off of.”

Logistically, Alexandre acts opposite Maslany any time two or more of the clones interact — which is quite frequently — and delivers a screen-worthy performance before being replaced during post-production. While many actors would balk at the seemingly thankless job, Alexandre considers it the role of a lifetime.

“I’d just graduated theater school and didn’t have much experience working on camera,” the 24-year-old told BuzzFeed of being cast in 2012. “I didn’t really know how complicated the role would become, but I’m working on such a wonderful show with such skilled people and learning so much. It’s incredible.”

And Alexandre has actually been involved with Orphan Black since before the cameras started rolling on the series, which is now in its second season. “I actually worked as a reader for the initial auditions when they were trying to find actors to play Sarah and Felix,” she said of roles that went to Maslany and Jordan Gavaris respectively. “I was aware of the show and already in the room with other people who were auditioning for the leads, so I knew the casting director, and she’s the one who brought me in to read for the double.”

Maslany said that it was imperative to Orphan Black creators Graeme Manson and John Fawcett that whoever was hired as the clone double be an actor, not a stand-in. And that led to an extensive — and elaborate — audition process. “The first audition I had was with a casting director and I did my interpretation of Sarah, Katya, and Alison,” Alexandre recalled.

“Then I had a callback with John doing my interpretation of the clones. Then, for the third audition, they brought Tatiana in and we were acting off one another. We’d play a scene and I’d watch her while she played opposite me. Then we’d flip, and I’d mimic her. Because they were really adamant on finding an actor as opposed to just a double, they were comparing me to her and how I worked off of her.”

In the two years that they’ve been working with one another, Maslany and Alexandre have developed an important short-hand and an unexpected reliance on one another. “There were times on set where I was so tired and I didn’t know how I was going to get through the day, and she would show up and give me everything,” Maslany said. “[She] knew how tired I was, and woke me up. She’s so there for me and so giving of all her energy. It’s the ultimate generosity.”

And Alexandre feels the same way about Maslany. “I’m grateful she’s created these characters, who are so interesting and layered, so I can explore them too,” she said.

Later this season, Alexandre will have her first on-screen appearance. “Throughout the first season, there were little murmurings of how we could get my face in a scene,” she said. “The writers kept saying they were going to find me something — and they did. I make an appearance as a character of my own in Episode 9. It’s a dream.”

Watch BuzzFeed’s exclusive behind-the-scenes feature from Season 2, Episode 1 below to see how Maslany and Alexandre work together: